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Misfiring and hesitating

curlo May 12, 2016

  1. curlo

    curlo Registered User

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    Evening chaps

    Any assistance would be gratefully received. I'm experiencing what I believe to be a misfiring throughout the rev range whilst the engine's under load. When looking to accelerate from around 2,000 rpm it's as if the car hesitates for a second or two after I apply the throttle before then leaping forward. This happens irrespective of whether I'm in 2nd, 3rd or 4th. First gear seems to be ok, but I haven't been able to find a bit of private road to be able to test it properly in 5th or 6th. Also, and this may just be me, but I could swear that the intake noise is a lot louder of recent too (I'm running a CTS turbo open cone intake).

    No fault codes are logged on the ECU and my local German car specialist independent can't seem to locate the source of the problem, claiming that all readings are spot on.

    The car is a 2.0 TFSI with 28k on the clock. Currently running a CTS K04 turbo with Revo Stage 3 map and Revo Stage 2 DSG software. The mods have been on the car since the summer of 2015 and new OEM coil packs and Iridium plugs were done at the same time. The car is my daily driver and was running perfectly until about 2 weeks ago. I've done a quick check with Torque Scan and it seems like there are some odd readings from the 02 sensors (see attached pic).

    Any ideas?

    Cheers in advance!
    screenshot.jpg
     
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  3. Smirky

    Smirky Registered User

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    I had a misfire at idle and @Alex_Wil had one up in the rev range MI e turned out to be a faulty injector and I believe Alex's was down to the lpfp so might be worth looking into
     
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  4. curlo

    curlo Registered User

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    Thanks @Smirky, I'll be sure to check those 2 things. I've been told by my garage that the fuel pressure is within range, but I'm going to take the car to a tuner this coming week to see if they've a different view.
     
    Alex_Wil likes this.
  5. Craig-P

    Craig-P Registered User

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    I would most certainly look at getting your injectors checked/tested and if needs be professionally cleaned or replaced.

    It appears to be a pretty common issue from what I've seen/read.
     
    curlo likes this.
  6. Alex_Wil

    Alex_Wil S3 - DSG - Black Edition - TTE Hybrid Turbo Regional Rep

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    My car when it had the misfire was also within the correct fuel range but when they changed the LPFP is was fine. Mine could of also been down to the map as that was changed also
     
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  7. curlo

    curlo Registered User

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    That's good advice - thanks Craig! If it's a common problem to our cars then I wonder what the underlying reason is?
     
  8. curlo

    curlo Registered User

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    That's interesting to hear, Alex. I would have thought that the fuel pressures/AFRs would have been out of range if the fuel pump was on the fritz, but then I guess you never know with cars! As you say, it may have been partially cured by the new map too. Either way, I'll get it checked. Cheers!
     
  9. curlo

    curlo Registered User

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    Update...

    So I took it to my local tuner and it turns out I was correct when I thought I could hear more whooshing coming from under the bonnet... However, rather than the noise being due to the intake, it's coming from what I'm told is a big hole/tear in the silicone hose attached to the outlet of the turbo (the bit that includes the branch off to the recirculation valve). I've highlighted the bit in the 2 pictures below.


    614.jpg 505.jpg

    Once I've got hold of a replacement and got the offending part in my hands then I'll post pictures of it up on here. Short of it somehow having been subjected to physical damage prior to being fitted, I'm not sure quite why it's split. I thought these silicone hoses were meant to be pretty strong...
     
  10. nil538

    nil538 Registered User

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    That's the Cai inlet hose mate not an outlet hose
     
  11. curlo

    curlo Registered User

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    So the replacement hose finally arrived from CTS in Canada: only took them 3 weeks to get it to me...

    And here's the offending hose. You can clearly see the split where it forks off to the recirculation valve. I'm pretty unimpressed with the quality of this hose, truth be told. I can easily squash the hose flat between two fingers, so I'm not actually that surprised that it blew out. The replacement hose seems to be stiffer and less easy to squash, so I'm hopeful that it will stay the course. I wonder if there was some sort of fault in the manufacturing process of the original??

    Either way the car's once again back to full strength, which is the important thing right? :grin:

    20160623_195440.jpg
     

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